Silent drive mechanism for talking motion picture machines



1.. DE FOREST ,806,744

May 26, 1931.

SILENT DRIVE MECHANISM FOR TALKING MOTION PICTURE IACHINES Filed lay 24, 1924 Patented May 26, 1931 UNITED 'STATES PATENT OFFICE" LEE DI FOB-EST, OF NEW YORK, N. Y., ASSIGNOB, BY MESNE ASSIGNMENTS, TO GENERAL TALKING PICTURES CORPORATION,

A CORPORATION OF DELAWARE SILENT DRIVE MECHANISM FOR TALKING MOTION PICTURE MACHINES Application filed May 24, 1924. Serial No. 715,499.

This invention relates to a silent drive mechanism for talking motion pictures or phonofilm pictures as they are now called in the art and has for its principal object the provision of means for eliminating mechanical noises in the photography and reproduction of sound waves.

A further object of the invention is to provide a silent drive mechanism of this character which is simple in structure, eflicient in operation and economical of manufacture, installation and maintenance.

Further objects of the invention will appear more fully hereinafter.

The invention consists substantially in the construction, combination, location and relative arrangement of parts, all as will be more fully hereinafter set forth as shown by the accompanying drawing and finally pointed out in the appended clalms.

Referrin to the drawing, the single figure illustrates l argely diagrammatically a silent 've mechanism embodying my invention.

In the talking motion picture or phonofilm art, particularly that branch of the art where sound waves are photographically recorded on motion picture film by means of a photographic attachment to a standard motion picture camera or projector, it is the customary practice to secure driving power of all the movable parts of the machine from a common source of power. This is ordinarily accomplished through the agency of intermediate mesh gears which are kept well lubricated to minimize the amount of noise incident to their operation.

In sound picture photography, however, where the sound record is obtained by varying light intensities, which operation is effected by sound waves, it will at once be readily apparent that it is of importance to eliminate as many extraneous noises and particu: larly mechanical or machine noises to thereby secure clear sound recording and consequently clear sound reproduction.

In accordance with my invention I propose to eliminate all intermediate gearing between the driving power and the intermittent feed sprocket, i. e., employ separate driving power for the feed sprocket which draws the film past the phonofilm attachment leaving the remainder of the moving parts of the machine which are power driven, to be driven from their usual source, in this way elimi- "nating all mechanical noises incident to the present type of power actuation employed.

The single figure of the drawing illustrates a practical embodiment of my inventive idea showing separate drives, for the sprockets.

Referring to the drawing, I show at. 1 the film reel on which is wound the film 2 which passes over the sprocket 3 and usual guide or tension rollers 4, 5, attachment 6, over sprockets 7 and 8. This is the usual practice in standard motion picture machines and has been diagrammatically illustrated only.

Heretofore all the sprockets 3, 7 and 8 have been ordinarily driven in synchronism from the same source of power. The sprocket 8 is on the main power shaft in the present constructions from which all of the parts of the machine are driven, including the intermittent feed sprocket not shown. The relative arrangement of the phonofilm attachment and the film gate is shown in my Patent No. 1,693,071, November 27, 1928. In accordancewith the present invention the sprockets 3 and 8 are driven in synchronism from any suitable source of power. These two sprockets may be connected together by means of gearing, chains, belts and the like, a manner which is well known and common in this art. In this invention the sprocket wheel 7 is driven by separate and independent sources ofpower represented by a motor 9, provided with a bevel gear 10 which meshes with the bevel gear 11, on the shaft 12. The otherend of the shaft 12 is propast the phonofilm gear 14 on the shaft 15. The shaft 15 supports the heavy fly-wheel 15 as well as the f sprocket 7. It will, of course, be apparent pllshed by employing for instance, electric motors running insynchronism in a manner which is well understood in the electrical art. By this arrangement the film is fed over the sprockets 3, 7 and 8, and through the phonofilm attachment. By means of the arrangement disclosed the film runs evenly and smoothly through the phonofilm attachment and 1) reason of the fact that feed sprocket 7 is riven from an independent source of power, the usual noises incident to the operation of the sprocket wheels are eliminated.

- I have found that with this type of drive exceptionally smooth operation of the sprocket 7 is secured and that no appreciable effect is had on the phonofilm attachment, as

a result thereof as distin bed from the iiect exceedingly damaging e of the noisy gear connection when all the sprockets 3, 7 and 8 are driven from the same source of power.

- attachment and means for driving the feed Many modifications and changes in detail and applications of the invention will readsaid machine for drawing the film through said attachment.

In testimony whereof I havehereunto set my hand on this twentieth day of May A. D.,

LEE DE FOREST.

11y occur to those skilled in the art and the Y adaptation thereof both for cameras and pro ecting machines will be readily apparent, and I, therefore, do not desire to be limited or restricted in this respect; but having now set forth the objects and nature of my invention, and having shown and described a structure embodying the principles thereof, what I claim as new and useful and of my own invention, and desire to secure by Letters Patent is: a I

-1. In a sound and motion picture machine employing afilm the combination with a phonofilm attachment of a plurality of film eedlng sprockets including a feed sprocket for drawing the film through said phonofilm splrocket for drawing the film through said P otherfeed sprockets.

2. ha sound and motion picture machine employlng a film the combination with a phonofilm attachment of a plurality of eed sprockets including a feed sprocket for drawing the film through said phonofilm attachment, power means, a connection between said power means and feed sprocket nclud ng a worm and worm gear for drivm said feed sprocket independently of the 0 er sprockets and means for .driving the other feed sprockets.

3. In a mechanism of the type described employing a motion picture film, the combination comprising a standard motion picture machine including means for advancing a onofilm attachment independently of the 

